1. Field of the Invention.
This invention relates to improvements in check valves, and more particularly, swing-type check valves.
2. Discussion of the Prior Art.
The part of a swing check valve most normally subject to wear and need of renewal or replacement is the valve seat. Thus, when the valve seat is an integral part of the valve body, and the seat becomes worn, the most commonly accepted practice is to replace the entire valve. Thus, it is desirable to have a replaceable valve seat.
The hanger, or hangers, in a swing check valve for journaling the hinge pin of the valve disc sometimes become worn, with the result that the valve disc may not always seat evenly on the valve seat, resulting in possible wear of the valve seat and therefore leakage through the valve when the valve is supposed to be closed. Similar problems occur in those designs of swing check valves where the hinge pin is loosely journaled on purpose to provide a "floating" movement of a valve disc to and from the seat.
A comparable problem exists in swing check valves where the hinge pin is secured in a mating bore formed transversely through the disc. In such constructions, the hinge pin bore is frequently not precisely parallel with the seating face of the disc, such that the disc will be hung at an angle to the valve seat and even closure around the entire sealing face of the valve seat is not obtained.